The present invention relates to apparatus for severing cigarette rods or the like. More particularly, the invention relates to improvements in apparatus, known as cutoffs, which are utilized for repeated severing of axially conveyed rods consisting of wrapped tobacco or filter material.
It is known to sever a continuous axially conveyed cigarette rod by resorting to a cutoff wherein a rotary carrier supports one or more knives each of which severs the rod during each revolution of the carrier and each of which is sharpened, either during each revolution of the carrier or at predetermined intervals. The rod thereby yields plain cigarettes of unit length or multiple unit length. Similar apparatus are utilized for the severing of a continuous filter rod which is to be subdivided into filter rod sections of desired length, e.g., of six or eight times unit length, depending upon the nature of the tipping machine wherein the filter rod sections are united with plain cigarettes, cigars or cigarillos to form filter cigarettes, cigars or cigarillos of unit length or multiple unit length. Such apparatus are further provided with means for advancing or feeding the knife or knives at required intervals or continuously so as to compensate for wear which develops as a result of severing as well as in response to sharpening of each knife. Still further, a conventional cutoff normally comprises a guide which supports the axially conveyed rod at the severing station and moves with the rod while the rod is being severed to yield sections of desired length. Such guide is or can be employed irrespective of whether the cutoff is used in a cigarette making or in a filter rod making machine. Cigarette making machines which utilize cutoffs of the above outlined character are known as Garant and SE 80, both produced by the assignee of the present application. A filter rod making machine which embodies a similar cutoff is known as KDF and is also produced by the assignee of the present application.
A drawback of heretofore known cutoffs is that the knife or knives must be replaced at frequent intervals. Thus, the dimensions of the knife or knives in a conventional cutoff are such that the wear thereupon rapidly reaches a stage at which the knife cannot be fed any longer and cannot be subjected to further grinding action because the stroke of the feeding mechanism for the knife is exhausted. This means that the machine must be arrested for the express purpose of replacing one or more spent knives with fresh knives. Since a cigarette making or filter rod making machine can turn out in excess of 100 cigarettes or filter rod sections per second, any stoppage entails pronounced losses in output. On the other hand, the wear upon the knives in a machine which operates at such a high speed is very pronounced so that the replacement of conventional knives at frequent intervals is unavoidable.